Tensioning device for the upper thread in a sewing machine



June 22 1965 FGEGAU'F, JR A 3,190,249

V"rENsIoNING DEVICE Fon' THE UPPER THREAD IN A SEWING MACHINE Filed Deo. 20, 1962 2 Sheets-Sheet 1 June 22, 1965 F. GEGAUF, JR

TENSI'NNG DEYICE FUR THE UPPER THREAD INIA SE'IHG MACHINE Filed Dec. 2D, 1962 2a 29303135 :4s-n.39 43 47 2 Shasta-Sheet 2 TENSINlNG DEVICE FR THE UPPER THREAD IN A SEWING MACHINE Fritz Geganf, 5r., Steckborn, Thurgau, Switzerland,

assigner to Fritz Gegauf Aktiengesellschaft, Bernina- Nhmaschinenfahrik, Steckhorn, Thurgau, Switzerland Filed Dec. 20, 1962, Ser. No.246,205 Claims prinrity, application Switzerland, Jan. lil, 195,2

253/ 62 5 Claims.` V(Cl. 112-254) The object of the present invention is to realize a tensioning device for the upper thread in a sewing machine, which device simplifies the threadingof the upper thread, technically improves the sewing and further improves the appearance of the sewing machinerby not being placed in the angle of View to the needle.

The tensioning devices for the upper thread known heretofore generally comprise a pair of tension disks placed outside of the sewing machine, a tensioning spring and an adjusting nut. In most of the cases thesetensioning devices are Vassembled as a unit together withthe Ithread control spring. placed below the lowermost position of the take-up lever, generally on the front side of the machine. Por the threading operation the upper thread must be threaded from the `bobbin, sitting on a support, through one or several open or closed thread eyes. Hereaiter the thread has to be guided between the tension disks and simultaneously suspended in the control spring; ThenV the thread is guided to theboring in the take-up lever over the rigid dehecting bolt or control stirrup controlled by the cloth bar. From here the further threading up to the needle is effected in the usual way.V lhis threading method is complicated` and requires precise instructions to the operator. Accordingto the construction these known tensioning devices protrude substantially from the housing 'of the sewing machine and hinder the free view of the needle and theV work. Recently thread tensioning Vdevices have been developed which are simplied in that the `tension `ing bolt and control stirrup are dispensed with: `These tensioning devices are of large size owing to the lever arm for the control spring which is require to havea determinated length. Since the housing of the Atensioning device is only partly mounted into the machine and since the protruding portion of this device also lies in the direction of view toward the needle and the work, such tensioning devices have a hindering efect. The operator has to look on both sides of the tensioning device, a drawback wmch may be compensated only by getting accustomed to it. Further sewing machines are known in which the tensioning device is arranged outside of the machine housing at any appropriate place, for'example onv the front side of the sewing machine arm, on the horizontal part thereof or` the like. Such machines Agenerally are forV industrial use Where a good appearanceris not of substantial importance. Inra sewing machine destined for the household, however, the appearance combined withV a simple operation is of utmost importance.

Always theseV tensioningk devices are Owing to this arrangement of the thread tension device there is obtained an additional thread length between the tensionrdevice and the control device which, technically seen and owing to the elasticity of the thread, represents a substantial advantage. Even in the case of a fall? j out of the control spring the sewing-machine may be operated. rlhemanner of threading in such a machine is substantially simplified by the fact that no closed thread eyes,.guiding bolts and control levers are present. Moreover, the angle of view to the needle is tree, an advantage which is of substantial importance. In particular this advantage is obtained by mounting the tensioningdevice known per se into the horizontal part of the sewing machine upper arm, whereby the tensioning surfaces of the thread tension disks lie within the Vwidth of a slot extending transversely through the upper arm and whereby the control of the tension is effected from the outside. Preferably, means may be provided to make visible from the outside the amount ofthe thread tension. Y

i Other features and advantages of the invention will become apparent from'the description now to follow, ofV a preferred embodiment thereof, given byV way of example only, and in which reference will be made to the accompanying drawing, in which:V

Y FIGURE l is a front-view of a sewing machine,-

to illustrate the window for the indicating device,

FIGURE 4 is a partial longitudinal sectional view of the upper part of the upper arm Vof the sewing machine with a double thread tensioning device, and j FIGURE 5 is a top view of the double threadtensioning device with a releasing lever and an indicating device, the upper wall of the arm being removed.

Reterringrnow tothe drawings, reference numeral 1 designates the base plate of the sewing machine onto which is mounted theupper arm 2. The Vhorizontal part ofthe arm-2 is closed by a cover 3 and the front side of the arm head is closed by a cover d from which projects a switch button S for the mounted light. The machine is driven in a known way by the belt of a handwheel 6. On

VOnthe backside of the machine there is provided a bobbin holderV l2 with two pins 173 and l. .adapted to receive bobbins. Reference numeral 15 designates a bobbin from which is withdrawn the sewing thread 16. Reference numeral 17 designa-tes the bolt of a pre-tensioning With the present invention for the first time a thread ,tensioning means hasV been developed, the tension disks device against which is pressed a tension disk 18 loaded by af spring 19.` Al transverse slot 20 in the cover 3 has ,on both sides thread guides y2l and 22. On the lowerside ofthe cover- 3 there'is arranged a supporting plate'23 with screws 24 and 25.` This plate carries a slotted thread tensioning bolt 26 held in position by a nut 27 andra resilient washer 28. In the transverse slot 20ct the cover S'there is' mounted a doublethread tensioning device comprising tension disks 29, 26, 31 in such manner'that the tension surfaces ofthe disks extend in parallel to the transverse slot Ztl. On both sides fof the tension disks there are arranged further washers 32 and 33. As well as the tension disks as also the washers 32 and 33 are maintained in positionby a pin 34 secured in the supporting plate 23. TheV tensioning pressure is transmitted by a pressure disk 35 engaging with its web 36 and slotted threadV tensioning bolt 26. A spring 37 bears against a flange 38 of an adjusting nut 39. The, latter comprises a coupling slot 40 engaged by drivers 4l and 42 of an Vof the thread tensioning Y tension release bolt 53 is housed in the hollow kthread* tension bolt 26V and presses against the web 36 of theV pressure disk 35- ActuationV of the pressure member 51Y FIGURE 4 is eiected by the in direction of Vthe arrow in pressure foot mechanism (not shown). Thepressure member 51 is maintained in position laterallybyl a lockV washer 54. YTo the supporting plate 23 there is pivotally Y mounted a double lever 55, 56. The pivoting axle for this double lever 55, 56 is formed by a shoulder. screw 57,. At the forward end of the leg 56 a scale is adjustably arranged; This scale is designated by YSti Vand carries a marking 59. -Itfis secured by a screw 60 and is adapted tol be tilted and disp-lacedV about a bolt 61. The leg 55 of the double lever 55, 56 bears Yagainst the flange 38 of the adjusting nut 39, The constant contact is ascertained by a torsion spring 62 wound about the bolt 57. One leg of spring 62 is connected withthe'leg 55 ofthe lever 55,

56 and the other leg of the'spring bears against thersupporting plate 23. The scale 58 appears in a window 63 of the cover.r 3. In this window 63 there is also provided Y surfaces of said disks extending transversely of said arm` Iand being located withinV said slot; and `tension `adjusting I claim: i

1. In. a sewing machine including a vertical standard supporting a substantially horizontal upper arm `having vupper surface andV betweensaid side surfaces, and havingV spring biased thread tensioning disks, the thread engaging i means operatively* associated with said disk, and ina marking 64 by means of which the thread tension may f be read. I

VThe upper thread is threaded into the machinerby means device mounted into dthis machine by-drawing the upper thread 16 between the bolt 17: and

- the tensionv disk 18, whereafter theY thread is laid into the transverse slot 20 so as Vto pass through the thread guide 2.2 and then between `the' tension disks 29, 30`andf30,131, respectively, and drawn oi at the thread guide 21.V .Here after the thread is suspended into the conti-019,Y threaded into the take-up lever Sand passed through the eye of the needle 11. The sewing machine is now-Y ready for operation. The thread tension is adjusted bythe adjust-k ing disk 43 protrudingin form of a segment from the cover 3. By turning this disk in direction of the cloth feed, `the adjusting nut 39 is moved toward the tensionv disk 29, 30, 31 and the pressure exerted by thetensionY disks onto the thread is increased. The double lever 55,Y

56 carrying the scale 58 indicates in the window the increase of the thread tension owing to the marking 59 moying to the right with lrespect to the counter-marking 64 in the window. If the control disk 43 is turnedin the cpj posite direction, then the marking 59'will move to the left.

The removal of the thread tension is eiected in a knownl manner by lmeans of the pressure` bar by lifting'the pres# sure plate at 51. Thereby the lever arm 52 presses onto the pin 53 which in turn lifts the tensiondisk 35 with the web 36 so that the pressure is nre'lased from the tension disks 29.,30,31 Y Y 4 Of course it is possible to modify the described arrangement in such manner thatin a sewing machine the upper arm of'which is closed a transverse' slot is made and moreover an opening in' which the thread or double thread tensioning device may be inserted. In such a .casethe indication for thethread tensionmay takeV placerdicluding amanual adjuster operatively associated `with said tension device and Vextending -to the exterior ofV said arm. Y

2. In arsewing machine, van V'upper thread tensioning device as claimedin claim 1, including a tension release device operatively associated with said disks; rand a supf` i port plate mounting vsaid thread tensioning device and` said tension release device, andremovably secured within said upper arm. e y

3. In a sewing.machine,an upper thread tensioning device as claimed in claim-2,l said upper arnrincludingxa cover extending longitudinally thereof and-forming :its upper surface; said slot being formed in said cover; said tensionrelease device being positioned on the inner` side Y -1 .gaged with Vsaid, bolt; saidmanual adjuster including a rectly at the adjusting disk in connectioniwith a rigid marking. However, such indication'then is not, as in the` described embodiment, in Vthe field of view of the operator.

rotatable knob having a disk'head and coupledtosaid'- nut to rotate said nut while providing for axial displacement of said nut relative to said vknob;`the disk head ofy saidV knob extending through a 'second upwardly opening slot extending transverselyofthe'` upper surface ofgsaid arm between said side surfaces,and spaced longitudinally trom said iirst slot; the width of said second kslot being of the order o f a thicknessof said disk headof said knob. Y 5. In a sewing machine,.an upper thread tensioning device as claimed'in claim'lincluding an indicating device i mounted on said supporting plate Vand having an innerY end coupled with saidtension adjustingl means for movementwithV the latter; said indicating device having an outer end carrying tension indicia; .the upper surfaces of said` arm beingA formed with a window therethrough, and. lanA Outer end of said indicating device being visible through said window.V

y References Cited by the Examiner.l

UNITED STATES PATENTS V.JORDAN FaANkLm, Primary Examiner, DAVID J. WnLIAMQWsKY, Examiner. 

1. IN A SEWING MACHINE INCLUDING A VERTICAL STANDARD SUPPORTING A SUBSTANTIALLY HORIZONTAL UPPER ARM HAVING AN UPPER SURFACE AND DEPENDING SIDE AND END SURFACE, AND THREAD CONTROL MEANS ON A SIDE SURFACE OF SAID ARM; AN UPWARDLY OPENING SLOT EXTENDING TRANSVERSELY OF THE UPPER SURFACE OF SAID ARM BETWEEN SAID SIDE SURFACES AND SUBSTANTIALLY ABOVE SAID THREAD CONTROL MEANS; AN UPPER THREAD TENSIONING DEVICE WITHIN SAID ARM BENEATH SAID UPPER SURFACE AND BETWEEN SAID SIDE SURFACES, AND HAVING SPRING BIASED THREAD TENSIONING DISKS, THE THREAD ENGAGING SURFACES OF SAID DISKS EXTENDING TRANSVERSELY OF SAID ARM AND BEING LOCATED WITHIN SAID SLOT; AND TENSION ADJUSTING MEANS OPERATIVELY ASSOCIATED WITH SAID DISK, AND INCLUDING A MANUAL ADJUSTER OPERATIVELY ASSOCIATED WITH SAID TENSION DEVICE AND EXTENDING TO THE EXTERIOR OF SAID ARM. 